CN110099093B

CN110099093B - Method, apparatus, computer program and computer readable medium for data communication

Info

Publication number: CN110099093B
Application number: CN201910094953.1A
Authority: CN
Inventors: 弗朗茨-约瑟夫·格茨; 马塞尔·基斯林; 于尔根·施米特
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2018-01-31
Filing date: 2019-01-30
Publication date: 2022-07-15
Anticipated expiration: 2039-01-30
Also published as: US20210120065A1; EP3522481A1; EP3695576A1; EP3522482B1; EP3695577A1; US11477107B2; WO2019149576A1; CN111670566B; US11296968B2; EP3522477B1; CN111670567A; US20210067571A1; WO2019149577A1; EP3522483A1; US20210075838A1; CN111684776B; EP3695576B1; US20190238441A1; CN111684776A; WO2019149466A1

Abstract

The invention relates to a method for data communication in a network, in particular an industrial network, for data transfer between a plurality of transmitters (11) providing data and a receiver (1) receiving the data provided by the plurality of transmitters (11) via a stream, the network having one or more nodes (2), wherein for establishing the stream a listener announcement message for the stream is issued by the receiver (1), which preferably comprises a stream description, and the listener announcement message is transmitted to at least one node (2) of the network. The invention further relates to a device for carrying out the method. Finally, the invention relates to a computer program and a computer-readable medium.

Description

Method, apparatus, computer program and computer readable medium for data communication

Technical Field

The invention relates to a method for data communication in a network, in particular an industrial network. The invention further relates to a device for carrying out the method. Finally, the invention relates to a computer program and a computer readable medium.

Background

Distributed industrial control applications require a guaranteed quality of service (QoS) or quality of service in the communication network connecting the terminal devices to each other, so that time-sensitive tasks can be performed by the network together with non-real-time related data communication (traffic). The end devices may be, for example, Programmable Logic controllers (SPS) (PLC), IO devices or protection devices.

Each connection for each application in the network that enables time-sensitive data communication between terminal devices must be registered and reserved in order to obtain guarantees from the network for lossless real-time delivery and on-time delivery of data frames. In this regard, the network must verify the availability of network resources (e.g., address table entries, frame buffering, delivery time slices) and allocate resources for each real-time data stream as long as they are available and guarantee access to the real-time data traffic.

Within the network, control information about registration, reservation and forwarding information has to be stored for each real-time data flow. The state of each reservation must be maintained. As the number of terminal devices and their real-time data communications on the same network increases, the amount of network control information also increases. This represents a serious scaling problem since storage and processing power is limited by the network nodes (e.g. bridges or switches). This is problematic especially in the case of combining one node and one terminal device in one single product, for example in an IO module with two switching ports for a line/ring topology (as in current ethernet factory floor solutions).

IEEE802.1TSN working group defines an extension IEEE802.1/.3 to the Ethernet standard for converged Time Sensitive Networks (TSNs). Based on previous work by the audio-video bridge (AVB) workgroup, the quality of service of the real-time data stream is further improved in terms of guaranteed delay. However, the state for each real-time data stream must still be maintained in the network.

The AVB introduces "multiple listeners per stream" to reduce the number of real-time data streams (IEEE802 called "streams") from one source (talker) to multiple destinations (listeners). The transmission of data from one source to multiple destinations is a typical AV (audio visual) application scenario, in particular for distributing audio data from a single source to multiple speakers. It is known that this Reservation model of AVB/TSN, i.e. the Multiple Stream Reservation Protocol ("MSRP"), supports Multiple listeners. Here, after a speaker announcement message (Talker advertisement) for a stream originating from a source, a multiple Listener join reservation (Listener join) may be performed, which results in a single stream control information entry. The forwarding from speaker to its listeners proceeds along a unique tree whose root (root) represents the speaker, where only one forwarding entry is needed for all stream listeners in the network node at the time. A single ethernet frame is distributed by one talker over the network to multiple listeners.

The model can be used in the industrial automation domain to apply multiple streams from one SPS representing a speaker to multiple IO devices representing listeners. In case a single stream is used, data for all "listening", i.e. receiving, IO devices may be delivered by the SPS. The number of streams in the network, and thus the amount of control information, is significantly reduced compared to the case where a separate stream for receiving data from the SPS is established for each IO device. Depending on the amount of data of the individual IO devices, the advantage of the simplified control information can be an overuse of the network bandwidth, since the individual IO devices only need a part (subset) of the information in the frames transmitted by the stream.

Since the closed loop control loop also requires a return channel from each IO device to the SPS, a generally large number of flows must be established in the network from each IO device to the SPS, i.e. for the "return direction". Ethernet frames requiring 64+ octets (octets) must be sent in each stream, even though the IO device only provides a few bits of input information for the SPS.

The real-time data stream in an AVB may have multiple frames in one period. However, AVB real-time streaming is associated with token shaping (CBS), which evenly distributes frames over the entire period. TSN allows the use of other shaping, such as strict priority, with the highest priority and bandwidth limitations of the real-time data stream to overcome the CBS limitations of this application scenario. In a TSN network, the burst data transmission rates for multiple frames are no longer evenly distributed over the entire period. Thus, all IO data can also be transmitted directly in succession by the network in a plurality of frames, which is typical for closed loop control applications.

Disclosure of Invention

The object of the invention is to provide a method of the type mentioned above which enables data communication in a network with reasonable effort, in particular in industrial networks in which the terminal devices have to communicate with one another in a closed control loop.

It is furthermore an object of the invention to provide an apparatus for carrying out such a method.

This object is achieved by a method for data communication in a network, in particular an industrial network, for data transfer between a plurality of transmitters providing data and a receiver receiving the data provided by the plurality of transmitters via a stream, the network having one or more nodes, wherein for establishing the stream a listener announcement message for the stream, preferably comprising a stream description, is output by the receiver and the listener announcement message is transmitted to at least one node of the network.

It is particularly proposed that the listener announcement message is propagated in the network, in particular transmitted to a plurality of, preferably all, nodes in the network.

It is further preferred that the listener announcement message is transmitted to a plurality of senders, wherein the transmission to the respective sender is in particular via a node or nodes located on a network path connecting the respective sender to the receiver.

In a further particularly preferred embodiment of the method according to the invention, it is provided that a speaker join message is sent out by at least one transmitter which wishes to transmit data to the receiver via a stream to react to a listener announcement message of the receiver, and that a speaker join reservation is carried out for the speaker join information at a node on the network path between the transmitter and the receiver. It is proposed in particular that in each case one speaker join message is transmitted by a plurality of transmitters, each of which wishes to transmit data to the receiver via a stream, in order to react to a listener announcement message of the receiver and that speaker join reservations are carried out at nodes on the network path between the respective transmitter and receiver.

The (respective) speaker join message preferably also comprises a stream ID and/or a reservation status.

It should be noted that as known from the prior art for stream establishment between a sender and one or more receivers, a reservation can or cannot succeed depending on: whether network resources are provided, in particular network resources that meet or do not meet the requirements described by the stream output by the receiver.

In other words, the present invention proposes to improve the existing reservation model, in particular such that it supports a "multiple talker per listener" configuration, in order to reduce the number of streams in case data from multiple sources/transmitters are to be transmitted to exactly one destination/receiver.

To this end, it is proposed according to the invention that the listener announcement message is output and in particular distributed in the network by at least one terminal device which wishes to receive data from a plurality of other terminal devices in the network, which thus forms a plurality of transmitters on behalf of the receiver and the other data providing devices. With the listener announcement message the terminal device forming the receiver informs that it wishes to receive data via one stream. The listener announcement message preferably comprises a stream description, in which case a plurality of transmitters may transmit data, in particular in the form of cyclically transmitted frames, via the stream to the receiver. The flow description includes, for example, forwarding address and bandwidth information.

In order to make it possible to have "multiple speakers per listener", the "listener announcement" introduces new properties or data objects that can be used within the framework of the reservation model according to the invention.

The newly set attributes or data objects according to the invention of the "listener announcement" correspond to the previously known "speaker announcement" in the case of streamed data transfer from a sender/speaker to one or more receivers/listeners, if compared to the prior art. The difference with the prior art is that one receiver wishing to obtain data via a stream issues an "announcement", whereas according to the prior art the sender does the announcement, i.e. the "talker announcement" is output by it and distributed to the possible receivers by nodes in the network. In the prior art measures, the traffic is carried out along network trees (Tree's), the start or Root (Root) of which forms a sender/talker and which is defined, in particular, by the integrity of the network paths through which the data arrives at a plurality of receivers/listeners.

The data transmission via the streams, in particular the cyclic transmission of frames from one transmitter to a plurality of receivers via one stream, is then effected in the same direction as the stream announcement, i.e. from the transmitter to the receivers along the network path of the tree.

In contrast, according to the invention, the streaming is effected by one receiver and is distributed in particular to a plurality of transmitters. In the newly set up property according to the invention, the root of the network tree is here a listener.

After a receiver outputs a listener announcement message and the message is preferably distributed and transmitted by a node in the network to the data providing device, i.e. the potential sender, the device wishing to transmit data to the receiver or by which the sender wishes to receive data may log on and perform resource reservation on the stream. To this end, in a particularly preferred embodiment of the invention, a further new attribute or data object is provided for reserving a "talker join" of the resource, which is output by the respective transmitter and causes a reservation at one or more nodes on the network path between the respective transmitter and receiver.

It should be noted that information about which devices in the network a receiver wishes to obtain data from may have been obtained previously by other means. This is similar to the AVB model, where the listener obtains the stream ID from the application used in the speaker announcement. For example, in an industrial environment, the information may come, for example, from an application that generates a program of SPS and IO devices, and obtain a free stream ID, for example, through a web service.

At this point, the resource reservation procedure after listener announcement is implemented in the opposite direction to the prior art, specifically not at the receiver side but at the transmitter side. The reservation along the respective network path starts in particular at the node closest to the respective transmitter and "propagates" in the direction of the receiver, whereas in the prior art (listener joining) the reservation starts at the node closest to the respective receiver and continues in the direction of the transmitter.

According to an advantageous embodiment of the method according to the present invention, at least one node, in particular at a plurality of nodes, the reservation status of a first port in the direction of one or more transmitters and the reservation status of a second port in the direction of one or more further transmitters are combined, and in particular the combined reservation status is forwarded in the direction of a receiver via one port.

It is particularly preferably provided that the node closest to the receiver forwards the consolidated reservation status for all senders to the receiver, wherein the reservation status in particular reached in the receiver comprises the information that the reservation of the sender-side ports of all nodes on the network path connecting the sender to the receiver is successful, or the reservation of the sender-side ports of all nodes on the network path connecting the sender to the receiver is unsuccessful, or the reservation of at least one sender-side port of at least one node on the network path connecting the sender to the receiver is unsuccessful, and the reservation of at least one sender-side port of at least one node on the network path connecting the sender to the receiver is successful.

It should be noted that the state merging function for the listener state is known from the prior art. In AVB networks, for example, the reservations are based on a single forwarding tree that is built using RSTP (rapid spanning tree protocol). The listener states are merged (merged) in the upward direction of the tree to one sender.

The reverse is (again) true in the above-described embodiments of the invention. Speaker states are merged (merged) in the upward direction of the tree to exactly one receiver.

Merging (merge) is not done from the listener state but from the talker state, whereas according to the measures known in the art the node reservation states arriving at the respective nodes through ports on the receiver side (i.e. the listener side) are merged and the frames are copied into the relevant nodes for the purpose of distributing the data to multiple destinations.

Here, a known protocol of the state merging function known to the receiver/listener may be cited or may be constructed based on this protocol, since the actual reservation of resources at one or more nodes may in principle run the same or similar as previously known measures.

In the method according to the invention, it can also be provided that at least one reservation protocol is used for reserving resources at one or more nodes. A previously known, in particular standard, reservation protocol can be cited, which is then preferably extended with at least one, in particular a plurality of, data objects. Examples of known standard reservation protocols, which can be applied in a particularly extended manner in the framework of the method according to the invention, are the Stream Reservation Protocol (SRP) and/or the multi-stream registration protocol (MSRP) and/or the resource reservation protocol (RSVP).

SRP is a known variation or extension of the ieee802.1q standard, which has been separately standardized as ieee802.1 qat.

At this point the listener announcement message and/or speaker join reservation particularly preferably represents a reservation protocol (e.g. SRP and/or MSRP and/or RSVP), an extended data object.

The new attributes or data objects for multi-talker reservation provided according to the present invention may be introduced in particular into existing standard stream reservation protocols without having to change the basic principle of real-time stream reservation.

It can also be provided, in particular when using the rapid spanning tree protocol, to determine a network tree which is formed by network paths which connect a receiver to transmitters which wish to transmit data to the receiver via a stream and by which a speaker join message is respectively transmitted.

The determined network tree (which may also be referred to as listener tree) belonging to a flow between a plurality of senders and one receiver preferably represents a data object that extends a reservation protocol (e.g. SRP and/or MSRP) for resource reservation.

The listener tree is generated by the listener announcement according to the invention and comprises in particular information about one listener port and preferably possibly a plurality of talker ports per node, in particular a bridge. The listener announcement given by one listener actually serves as a new logical root of the tree for reservations.

In this case, the data transmission, in particular in the form of cyclically transmitted frames, from the plurality of transmitters to the receiver after the listener announcement and the talker join, in particular after a reservation, takes place in the opposite direction to the listener announcement, i.e. from the respective transmitter to the receiver, i.e. in the "reservation direction".

In a further advantageous embodiment, it is provided that the listener announcement message comprises a stream description having an indication of the stream type, wherein preferably the cumulative stream or the multiplexed stream is given as the stream type.

In particular, in the cumulative stream type, it is proposed that frames are transmitted to the receiver by all transmitters participating in the stream in each cycle, wherein this "data accumulation" leads to a greater bandwidth, but achieves a low latency, since all transmitters can transmit "simultaneously". However, for the cumulative flow type, frames must be buffered in the bridge, since only a reserved number of frames per cycle can be forwarded via the listener-side ports.

In contrast, depending on the type of multiplex stream, only one transmitter's frame is transmitted in each cycle, i.e., waiting is performed. The multiplexed stream type suffices to use a smaller bandwidth, but requires a longer time before data arrives in the receiver because it is transmitted sequentially. One type or the other can be decided according to the specific requirements of a given application scenario.

The present invention allows for the first time "multiple speakers for one real-time stream/stream", the present invention provides a number of significant advantages. On the one hand, the number of real-time streams, i.e. the number of streams in the network, is reduced. Thereby resulting in a reduced control overhead for registration and reservation of flows and a reduced number of filter database entries in the node, and the same overhead (overlap) is achieved for both directions of data transfer. Furthermore, scalability is improved as more terminal devices, in particular sensors/actuators, can be supported. Furthermore, the measures according to the invention are independent of a given network topology. It is therefore by no means limited to e.g. a line topology, but may equally well be used in the presence of other network topologies, such as a ring or star topology. Furthermore, the communication configuration is simplified by the measures according to the invention. It is also possible to simplify the engineering planning of the control application, in particular to achieve an automatic communication configuration without engineering planning, and to simplify the control information of the field bus application.

Whether a stream exists between a receiver and a plurality of transmitters in the sense of the present invention can in particular be seen in that exactly one stream ID exists and a plurality of transmitters transmit data to a receiver via one stream with one ID. The same stream destination address can be used for data of a plurality of transmitters.

It is clear that in a network, a plurality of streams can be set up, by means of which data can accordingly be exchanged in a communication partner group formed by exactly one receiver and two or more transmitters, that is to say a plurality of streams can be set up in the manner according to the invention with listener announcements and speaker(s) entry.

Alternatively or additionally, the above object may be achieved by a method for data communication in a network, in particular an industrial network, having one or more nodes, wherein a stream is established between a plurality of transmitters and a receiver and/or data is transmitted by a plurality of transmitters to a receiver by means of a stream.

Another object of the invention is a control method for an industrial-technical process or vehicle, in which, between at least two components of a control system, in particular between one or more sensors of the industrial automation installation or vehicle as transmitter and preferably exactly one controller of the industrial automation installation or vehicle as receiver, in particular an SPS, data are exchanged and a control of the industrial-technical process or vehicle is effected on the basis of the exchanged data, with the method for data communication according to the invention being carried out.

Another subject of the invention is an apparatus comprising

At least one, preferably a plurality of nodes, in particular bridges, and/or

At least one, preferably a plurality of terminal devices, in particular sensors, each forming a transmitter, and/or

A device forming a receiver, in particular a controller of an industrial automation installation or of a vehicle,

wherein the device is designed and arranged to carry out the method according to the invention for data communication or the control method according to the invention.

The device according to the invention can be part of a control system for an industrial-technical process, for example, which control system then forms a further subject matter of the invention.

Furthermore, the invention relates to a computer program comprising program code means for performing the steps of the method for data communication according to the invention or of the control method according to the invention, and to a computer-readable medium comprising instructions which, when executed on at least one computer, cause the at least one computer to perform the steps of the method for data communication according to the invention or of the control method according to the invention. It should be noted that a computer-readable medium should not only be understood as a physical medium, but it may also exist, for example, in the form of a data stream and/or a signal representing a data stream.

Drawings

Further features and advantages of the invention will become more apparent from the following description of embodiments of the method of the invention with reference to the accompanying drawings. In which is shown:

FIG. 1 is a schematic partial view of an industrial network illustrating a situation where one sender transmits data via a stream to multiple receivers;

FIG. 2 is a schematic partial view of an industrial network illustrating a case where one receiver receives data from a plurality of transmitters via streams;

FIG. 3 is a schematic diagram of a bridge at which two listener states are merged (merge);

FIG. 4 is a schematic diagram of a bridge at which two talker states are merged (merge);

FIG. 5 is an overview of a new data object compared to the prior art; and is

Fig. 6 is a schematic diagram for explaining the types of the accumulated and multiplexed streams.

Detailed Description

Fig. 1 shows a schematic partial diagram of an industrial ethernet based network. In particular, a terminal device is to be recognized, which represents a transmitter/speaker 1, and is connected via a plurality of bridges 2 (only four of which are shown in fig. 1) to a plurality of further terminal devices, which each represent a receiver/listener 3. Three of the receivers 3 should be identified in fig. 1. The three points on the right in the figure are intended to illustrate that the bridge 2 above the right is followed (possibly) by other bridges 2 and terminal devices.

As can be seen from fig. 1, in the illustrated embodiment, the ethernet-based network with multiple bridges 2 is characterized by a linear topology. Of course, other network topologies known from the prior art may also be provided, for example tree, star or ring topologies.

The terminal device forming the transmitter 1 is currently an SPS of an industrial automation installation, and the terminal device forming the receiver 3 is an actuator of the automation installation, which requires a periodic control signal from the SPS, so that a periodic influence on an industrial-technical process, not shown in the figure, occurs.

The control signal is transmitted from the SPS1 to the actuator 3 through an ethernet-based network. The communication of the control signals from the SPS1 to the actuators 3 is here implemented in the form of frames, which are transmitted by streams in the network. In particular, this type of data communication, for example known from the AVB and TSN standards, ensures compliance with preset delay times, which can vary from stream to stream and are in particular relevant for the respective application. It is thus ensured that the control signal reaches the actuator 3 within a predetermined maximum delay time, i.e. the maximum delay time elapses from the feeding of the data into the network by the SPS1 until the data enters the actuator 3. Thus, for example, a particularly real-time critical communication between the SPS1 and the actuator 3 can be ensured.

It applies here that, with reference to the associated stream reservation protocol (stream reservation protocol SRP), a stream is set up, which is specified, for example, by the audio/video bridge (AVB) task group and in particular by the time-sensitive network (TSN) task group in international standard IEE802.1, but only one stream is available between one transmitter and one receiver or also between one transmitter and a plurality of receivers. The latter configuration corresponds to the configuration recognizable in fig. 1.

In order to establish a flow between the SPS1 and the actuators 3 according to the known standard, a reservation is made at each of the bridges 2 with an SRP, the bridges being located on, i.e. connected by, a network path between the SPS1 and the respective actuator 3. Here, the SPS represents a data source called a talker, the presence of a stream is informed by SPS1 in a first step with talker announcements, and the properties of the stream are described by SPS1 forming the talker. In particular, data initiated by SPS1 for it is passed to the egress ID, forwarding address, and bandwidth information.

The announcement about the flow is distributed to all nodes, here to bridges 2 in the network, wherein each bridge 2 now directs the information of the receiving port, i.e. the port in the direction of the talker 1, that the announcement arrives through this port and subsequently the data also arrives. Since according to the prior art the data source is also referred to as talker 1, this port is also referred to as talker port. The ports in the direction of the listener/listeners are also referred to as transmitter or listener ports, respectively.

One or more listeners, currently actuators 3, are registered in the stream provided by SPS 1.

At the bridge 2 located between the talker 1 and the respective listener 3, at the ports in the direction of the listener, i.e. at the listener ports, reservations are performed separately according to the flow description given by the SPS1 representing the talker, as long as the available resources at the respective bridge 2 are sufficient. Each node 2 checks whether its internal resources are sufficient for the performance required in the framework of the flow to be established, in particular with regard to the data volume and the data throughput. If this is the case, node 2 reserves these resources for the flow to be established and forwards the aggressive reservation status to the subsequent bridge 2 or to the last bridge at sender 1.

By means of the reservation, each node 2 can ensure that it guarantees the required performance during the subsequent data transfer. This is the difference between a flow and an unprotected connection.

If the resources are not sufficient, a negative reservation status will be forwarded.

Here, the reservation starts at the respective receiver/listener, i.e. the bridge 2 closest to the actuator 3 and "propagates" along the respective network path to the data source/talker, i.e. the SPS 1. Thus, the reservation of resources in the bridge 2 is effected in the opposite direction to the forwarding of control signals from the SPS1 to the actuator 3, which forwarding is effected by the flow when the reservation at the bridge 2 succeeds. The direction of the subsequent data transmission is depicted in fig. 1 by the arrow 4 and the upper block picture element, indicated with 5, which represents the forwarded frame purely schematically.

Here, the reservations are based on a forwarding tree, called a speaker tree, which can be constructed using the Rapid Spanning Tree Protocol (RSTP).

At the bridge 2 forming the branch, i.e. the data has to be forwarded through the ports on both listener sides, a "merging" of the arriving listener reservations takes place. This is achieved by the "state merging" function of the reservation protocol used.

Fig. 3 shows a purely schematic representation of the bridge 2, from whose ports two listener-side ports 6 and one talker-side port 7 can be identified.

The "listener state merging" function, which is purely schematically represented by block picture elements in the direction of the speaker 1, is denoted by 8. The arrow marked 9 also represents the merged listener reservation states arriving through port 6 on the listener side and output through port 7 on the talker side. In case only a successful reservation (listener ready) arrives at port 6 on the listener side, the successful reservation (listener ready) is forwarded to port 7. In case of at least one successful reservation (listener ready) and at least one failed reservation (listener request failed-e.g. due to insufficient resources at the bridge located downstream of port 6), the listener ready failure is forwarded as a merged state. In case of only a failed reservation (listener request failed), the failure status (listener request failed) is forwarded.

In addition, the direction of frame forwarding, i.e. the direction of data flow, represented by arrow 10 is shown purely schematically in fig. 3. In order to make the frame 5 provided by the SPS1 forwarded through the ports 6, 7 of the two listener sides of the bridge 2 shown, a duplication (multicasting) of the frame 5 takes place.

The above has proven to be suitable for real-time critical transmission of control signals from the SPS1 to the plurality of actuators 3. Using only one stream with one stream ID, data can be provided to multiple listeners, which guarantees reasonable network consumption.

However, in addition to the situation shown in fig. 1, in which the control signal is distributed from one terminal device to a plurality of other network participants, there are also situations in reverse-particularly in industrial applications, in which data is transmitted from two or more sources to a (common) destination. This is the case, for example, in an automation installation, where the actual values acquired by a plurality of sensors are transmitted in real time to a central controller, which in turn may be provided by the SPS 1.

This situation is illustrated in fig. 2, which again shows a purely schematic partial view of an industrial ethernet based network, wherein the terminal device is again provided by the SPS1, but which now represents a receiver/listener and there are a plurality of transmitters/speakers, in particular a plurality of sensors 11, of which three can be seen in total in fig. 2. The industrial network with the bridge 2 and the terminal devices of fig. 2 is a component of an embodiment of the device according to the invention for carrying out the method according to the invention.

It should be noted that the network topologies are shown consistently in fig. 1 and 2, since here the actuators 3 identifiable in fig. 1 and the sensors 11 identifiable in fig. 2, respectively, are contained in the terminal device, but this is of course not necessary.

The SPS1 and the sensor 11 are correspondingly connected to each other via a plurality of bridges 2 in a purely optional linear topology.

According to the prior art, in order to transmit the actual values detected by the sensors 11 to the SPS1, a respective stream must be established for each sensor 11. For three sensors 11 that can be identified in fig. 2, three separate flows would accordingly be required, which would result in a significantly increased network management and processing effort compared to the situation according to fig. 1.

The present invention proposes to perform a new type of reservation, which implements a configuration of "multiple talkers per listener" in order to reduce the number of streams in case data is to be transmitted from multiple sources/transmitters to exactly one destination/receiver, so that three transmitters 11 can transmit data to the SPS1 through only one stream with one stream ID.

In particular, to this end, in a first step of the embodiment described herein of the method according to the invention, a listener announcement message for the stream is output by the receiver, i.e. the SPS1, which includes the stream description, and the listener announcement message is distributed in the network via the bridge 2 and transmitted to the sensors 11. With the listener announcement messages, the SPS1 informs in the network that it wishes to receive data via the stream. It should be noted that the information that sensor 11 may provide actual values to SPS1 has been provided by other means. This is also necessary in fig. 1 according to the prior art and can be done, for example, in an industrial environment during programming of SPS1 and IO modules.

After the SPS1 outputs the listener announcement and has distributed it, each sensor 11 that should transmit the actual value detected to the SPS1 outputs a talker join message. In the illustrated embodiment, all three sensors 11 send speaker join messages. For each of the three sensors 11, a speaker join reservation is now performed at bridge 2 on the network path between the respective sensor 11 and the SPS 1. The talker join message also includes a stream ID and a reservation status.

In contrast to the prior art, the resource reservation in bridge 2 is effected in the direction of one listener 1 (i.e. in the same direction as the forwarding of the actual value from sensor 11 to SPS1) starting from the respective talker (i.e. the respective sensor 11), and this forwarding is effected via a stream when the reservation at bridge 2 is successful. The direction of the subsequent data transmission is illustrated in fig. 2-analogously to fig. 1-by the arrow 12 and the block picture elements marked 13, 14, 15, 16, which represent the forwarded frame purely schematically above.

At the bridges 2 forming the branches, i.e. where data arrives through ports on both talker sides, a "merging" of the arriving talker reservation states takes place. This is achieved by the "state merging" function of the reservation protocol used, similar to the measures described in connection with fig. 1. Here, a reservation protocol is used which is extended with new data objects (listener announcement and talker join) and which refers to a known protocol of the listener state merging function known to the receiver/listener, since the actual reservation of resources at one or more nodes can in principle be run with one transmitter/talker and multiple receivers/listeners the same or similar to the previously known measures.

Unlike the prior art, at this point, the talker states merge into exactly one receiver, the SPS1, in the direction of the listener tree.

The listener tree is composed of additional new listener announcement data objects of the used extended reservation protocol, which are currently also determined using the rapid spanning tree protocol. The tree is here created by a saved port announced by the listener.

New data object listener announcement L_AdvertiseSpeaker joining in T_JoinAnd listener tree L generated by announcement_TreeCan be seen on the right side of fig. 5, respectively as opposed to the corresponding data objects of the previously known standard, i.e. the speaker announces T_AdvertiseThe listener adds L_JoinAnd speaker tree T_TreeShown in the left half of fig. 5. The number brackets mark the new data object above the two.

In fig. 4, the "merging" of talker states is shown purely schematically-and in a manner corresponding to the listener state of the "merging" of fig. 3. Here also bridge 2 can be seen, from which two talker side ports 17 and one listener side port 18 are shown. Furthermore, the "speaker state merging" function in the direction of the listener (i.e. the SPS1 marked 19 in the figure) is shown purely schematically by block picture elements.

It can also be seen from fig. 4 that in the measure according to the invention, the speaker reservation state and the forwarding of data are implemented in the same direction, both in the direction of one receiver, i.e. in the direction of SPS 1.

Furthermore, the direction of frame forwarding, i.e. the direction of the data flow, is shown purely schematically in fig. 4, which is indicated by arrow 20, and the merged speaker reservation state, which comes in through speaker-side port 17 and is output via listener-side port 18, is shown, correspondingly indicated by arrow 21. All reservation states of all talkers (i.e. all sensors 11) joining the (join) SPS1 stream informed by the listener announcement are forwarded to the SPS1 by the bridge 2 closest to the listener, i.e. the SPS1, which forms the logical root (root). Here, the merge reservation state in SPS1 is reached or includes the following information: the reservation of port 17 on the transmitter side of all bridges 2 succeeds on the network path connecting sensor 11 to SPS 1; or include the following information: the reservation of port 17 on the transmitter side of all bridges 2 is unsuccessful on the network path connecting sensor 11 to SPS 1; or include the following information: the reservation of at least one transmitter-side port 17 of at least one bridge 2 is unsuccessful and the reservation of at least one transmitter-side port 17 is successful on the network path connecting the sensor 11 with the SPS 1.

If the speaker reservation is successful for all relevant nodes, i.e. all bridges 2 on the listener tree, the actual data transfer can be started, i.e. the

frames

13, 14, 15, 16 with the actual values detected by the sensor 11 are forwarded.

The forwarding of

frames

13, 14, 15, 16 arriving at the bridge 2 from different sensors 11 via two talker-side ports 17 through one listener-side port 6, 7 can be implemented in different ways, for example according to a cumulative stream type or a multiplexed stream type. In the first type, all sensors 11 can transmit one

frame

13, 14, 15, 16 in one period, wherein the sum of all

frames

13, 14, 15, 16 must be reserved at this time, i.e. a larger bandwidth is required. In the multiplexed stream type, coordination is such that only one of the sensors 11 transmits a frame in each cycle, which results in lower bandwidth requirements but longer latency time because it takes longer before all sensors 11 have finished transmitting their data in turn. The stream type is part of the stream description that the SPS1 outputs with the listener announcement.

Fig. 6 shows a purely schematic comparison of the principle of the cumulative stream and the multiplexed stream types. In particular, periods #1 to #4 and frames 13, 14, 15 are exemplarily shown on the left side of fig. 6, i.e. in the cumulative stream type three

frames

13, 14, 15 are transmitted in each period, which is accompanied by a higher bandwidth 22, and only one

frame

13, 14, 15, respectively, is forwarded in each period according to the multiplexed stream type, wherein the bandwidth 22 corresponds to the bandwidth of the largest frame 13.

Based on the actual values obtained, the SPS1 can derive, inter alia, control signals in a manner known per se, and/or the actual values can be used for evaluation purposes. In addition, SPS1 influences industrial-technical processes, in particular, on the basis of the actual values obtained.

The measures according to the invention described above provide a number of significant advantages. On the one hand, the number of real-time streams, i.e. the number of streams in the network, is reduced. There is no longer a need to establish a separate stream for each sensor 11 transmitting data to the SPS1, but multiple sensors 11 may transmit data to a common destination via only one stream. This results in a reduced control overhead for registration and reservation of real-time flows and a reduced number of filter database entries in node 2 and the same overhead is achieved for both directions of data transfer required for closed-loop control. Furthermore, scalability is improved as more terminal devices, in particular sensors/

actuators

11, 3, can be supported. Furthermore, the measures according to the invention are independent of a given network topology. It is therefore in no way limited to the line topology shown, but may equally be used in the presence of other network topologies, such as ring or star topologies. Furthermore, the communication configuration is simplified by the measures according to the invention. It is also possible to simplify the engineering planning of the control application, in particular to achieve an automatic communication configuration without engineering planning, and to simplify the control information of the field bus application.

Although the invention has been illustrated and described in detail in the context of preferred embodiments, the invention is not limited to the disclosed examples and other variants can be derived therefrom by those skilled in the art without departing from the scope of protection of the invention.

Claims

1. Method for data communication in an industrial network for data transfer between a plurality of senders (11) providing data and a receiver (1) receiving said data provided by a plurality of said senders (11) via a stream, said network having one or more nodes (2), wherein for establishing said stream a listener announcement message for said stream is output by said receiver (1), a talker join message is sent by at least one sender (11) wishing to transmit data to said receiver (1) via said stream to react to said listener announcement message of said receiver, said listener announcement message comprising a stream description, and said listener announcement message is transmitted to at least one of said nodes (2) of said network, at least one node (2) a reservation status of a first port (17) in the direction of one or more senders (11) and a second end are merged The reservation status of a port (17) in the direction of one or more further transmitters (11), and the merged reservation status is forwarded in the direction of the receiver (1) via a port (21).

2. The method of claim 1, wherein the listener announcement message is propagated in the network, the listener announcement message being transmitted to a plurality of the nodes (2) in the network.

3. The method according to claim 1 or 2, characterized in that the listener announcement messages are transmitted to a plurality of senders (11), wherein the transmission to the respective senders (11) is made through a node (2) or a plurality of nodes (2) located on a network path connecting the respective sender (11) with the receiver (1).

4. The method according to claim 1 or 2, characterized in that at the node (2) on the network path between the transmitter (11) and the receiver (1), speaker join reservation is performed for the speaker join message, one speaker join message is transmitted by a plurality of transmitters (11) respectively wishing to transmit data via the stream to the receiver (1), and speaker join reservation is performed at the node (2) on the network path between the respective transmitter (11) and the receiver (1).

5. The method of claim 4, wherein the respective speaker join message comprises a stream ID and/or a reservation status.

6. Method according to claim 1, characterized in that the node (2) closest to the receiver (1) forwards a reservation status merged for all senders (11) to the receiver (1), wherein the reservation status arriving at the receiver (1) comprises an information: that is, the reservation of the sender-side ports (17) of all nodes (2) on the network path connecting the sender (11) with the receiver (1) is successful, or the reservation of the sender-side ports (17) of all nodes (2) on the network path connecting the sender (11) with the receiver (1) is unsuccessful, or the reservation of at least one sender-side port (17) of at least one node (2) on the network path connecting the sender (11) with the receiver (1) is unsuccessful, and the reservation of at least one sender-side port (17) of at least one node (2) on the network path connecting the sender (11) with the receiver (1) is successful.

7. Method according to claim 4, characterized in that for reserving resources at one or more of said nodes at least one standardized reservation protocol is used, which standardized reservation protocol extends at least one data object, wherein the listener announcement message and/or the speaker join reservation represents the data object extending the reservation protocol.

8. Method according to claim 1 or 2, characterized in that a network tree is determined using the rapid spanning tree protocol, which network tree is formed by network paths which connect the receiver (1) with transmitters (11) which wish to transmit data via a stream to the receiver (1) and by which transmitters a speaker join message is transmitted in each case.

9. The method of claim 7, wherein the determined network tree represents a data object that extends the standardized reservation protocol.

10. Method according to claim 1 or 2, wherein the listener announcement message comprises a stream description having a specification of a stream type, wherein an accumulated stream or a multiplexed stream is given as a stream type.

11. A method for data communication in an industrial network, the network having one or more nodes (2), the method according to any one of the preceding claims, wherein a stream is established between a plurality of transmitters (11) and one receiver (1), and/or data is transmitted by a plurality of transmitters (11) to one receiver (1) via a stream.

12. A control method for an industrial-technical process or a vehicle, wherein data are exchanged between at least two components of a control system while carrying out the method according to one of the preceding claims, and a control of the industrial-technical process or the vehicle is carried out on the basis of the exchanged data.

13. An apparatus designed and arranged to perform the method according to any of the preceding claims, comprising

At least one node, and/or

At least one terminal device forming a transmitter, and/or

An apparatus forming a receiver.

14. The apparatus according to claim 13, the node being a bridge (2), the terminal device forming one transmitter being a sensor (11), the device forming a receiver being a controller (1) of an industrial automation installation or of a vehicle.

15. A control system of an industrial technical process, comprising an apparatus according to claim 13.

16. A computer-readable medium comprising instructions which, when executed on at least one computer, cause the at least one computer to carry out the steps of the method according to any one of claims 1 to 12.